Contact lens, types, and proper usage and maintenance Video clips included on proper contact lens care!

2. What is a Contact Lens?
• Artificial device whose front surface
substitutes the antr. surface of the cornea
• Used for correction of:
1. Refractive error
2. Irregularities on front surface of cornea

3. Contact Lens Specifications
Diameter
1. Overall diameter (OD)
2. Optic zone diameter (OZ)

4. Curves
• Base curve (BC) or central postr. curve (CPC)
• Peripheral curves 1.intermediate (IPC)
2.peripheral (PPC)
• Central antr. curve (CAC) or front curve (FC)
• Peripheral antr. curve (PAC)
• Intermediate antr. curve (IAC)

5. Edge
• Union of the Peri.Postr.C & Peri.Antr.C of the
lens
Power
• Central anterior curve determines the power
of the lens
• Measured in terms of posterior vertex power
in diopters

6. Thickness
• Measured in the centre of the lens
• Varies depending upon the postr. vertex
power of the lens
Tint
• Color of the lens

7. Types of Contact Lenses
Hard Lens
Rigid Gas Permeable Lens
Soft Lens

8. Hard Lens
• From PMMA (polymethylmethacrylate)
• High optical quality, stability, light weight,
nontoxic, durable & cheap
• Diameter of 8.5-10 mm
• Disadvantages: 1. restricting the tolerance
2. corneal abrasions
3. stable tear film

9. Rigid Gas Permeable Lens
• Material permeable to oxygen
• Hard, but called as semisoft lenses
• Manufactured from:
1. Copolymer of PMMA
2. Silicone containing vinyl monomer
3. Cellulose acetate butyrate

10. Soft Lens
• HEMA (hydroxymethymethacrylate)
• About 1-2 mm larger than corneal diameter
• Advantages: 1. comfortable
2. well tolerated

11. Soft Lens
• Disadvantages:
1. Wettability
2. Proteinaceous deposits
3. Can get torn
4. Limited life
5. Inferior optical quality
6. Increased risk of corneal infections
7. Cannot correct astigmatism > 2D

12. Soft Lens
• Types:
▪ Disposable or Non-Disposable
▪ Clear or Colored
▪ Spherical or Toric
▪ Extended Wear
▪ Multifocal

13. Spherical Soft Lens
• A spherical contact lens is one in which both
the inner and outer optical surfaces are
portions of a sphere
• Corrects both short- and long- sightedness
• Cheapest & most comfortable
• Easy to get in a disposable form

14. Toric Soft Lens
• A toric lens is one in which either or both of
the optical surfaces have the effect of a
cylindrical lens, usually in combination with
the effect of a spherical lens
• Corrects astigmatism
• Lens is specially weighted to conform to
irregular cornea
• More expensive than spherical
• Some are available in disposable

15. Disposable Soft Lens
• Daily, two-weekly or monthly replacement
• Very simple cleaning (no cleaning for daily)
• Latest designs and materials
• Very popular

16. Colored Contact Lens
• Handling tint
– Useful when inserting or removing lens
• Enhancing tint
– Makes light coloured eyes more vivid
• Opaque tint
– Can change colour of eyes

17. Colored Contact Lens

18. Extended Wear Contact Lens
• New technology
• Made from silicone material which transmits
oxygen well
• Can wear for up to thirty days without
removing

19. MultiFocal Contact Lenses
• Can have dual focus lenses
• New technology → More expensive
• Available as disposable lenses

20. Indications
• Optical
• Therapeutic
• Preventive
• Diagnostic
• Operative
• Cosmetic
• Occupational

21. Optical Indications
• Anisometropia
• Unilateral Aphakia
• High Myopia
• Keratoconus
• Irregular Astigmatism

22. Advantage Over Specs
• Can correct irregular astigmatism
• Normal field of vision
• No aberrations
• Binocular vision in high anisometropia
• No condensation of rain or fog
• Cosmetically more acceptable

23. Therapeutic Indications
• Diseases of Cornea
• Diseases of Iris
• Glaucoma
• Amblyopia
• Bandage Soft Contact Lenses

24. Preventive Indications
• Prevention of symblepharon and restoration
of fornices in chemical burns
• Exposure keratitis
• Trichiasis

25. Diagnostic Indications
• Gonioscopy
• Electroretinography
• Examination of fundus in case of irregular
corneal astigmatism
• Fundus photography
• Goldmann’s 3 mirror examination

26. Operative Indications
• Goniotomy operation for congenital glaucoma
• Vitrectomy
• Endocular photocoagulation

27. Cosmetic Indications
• Unsightly corneal scars
• Ptosis
• Cosmetic scleral lenses in phthisis bulbi

28. Occupational Indications
• Sportsmen
• Pilots
• Actors

29. ContraIndications
• Mental Incompetence/Poor Motivation
• Chronic Dacryocystitis
• Chronic Blepharitis and Recurrent Styes
• Chronic Conjunctivitis
• Dry-Eye Syndrome
• Corneal Dystrophies and Degenerations
• Recurrent diseases like Episcleritis, Scleritis &
Iridocyclitis

30. Hygeine

31. Complications

32. The End